Dual-molecule enhanced MXene films for high specific capacitance in supercapacitors

In order to solve the problem of restacking the two-dimensional layered structure of MXene without causing a decrease in its conductivity, electrochemical performance , and flexibility, this study innovatively proposes a dual-molecule synergistic strategy utilizing polypyrrole (ppy) and 4-O-TEMPO (TEMPO = 2,2,6,6-tetramethylpiperidinyl-1-oxyl) to achieve high-capacitance MXene films. In this strategy, 4-O-TEMPO anchors to the surface and edges of Ti 3 C 2 T x nanosheets through hydrogen and covalent bonds , with its nitroxide radicals participating in redox reactions to contribute additional pseudocapacitance. Additionally, ppy enhances the conductivity of the composite film by shortening the electron transport path and prevents MXene from excessive oxidized by 4-O-TEMPO. This bimolecular strategy effectively alleviates interlayer stacking in MXene while maintaining its conductivity and flexibility. Density functional theory (DFT) calculations reveal that Ti 3 C 2 O 2 has stable interactions with 4-O-TEMPO, and the ternary system demonstrates excellent electronic and ion transport properties. As a result, the ppy/MXene/4-O-TEMPO (pMT) electrode achieves a specific capacitance of 530 F g −1 at 1 A g −1 and retains 300 F g −1 at 50 A g −1 . Additionally, the asymmetric supercapacitor reaches 23.8 Wh kg −1 energy density at 300.2 W kg −1 power density. • Dual-molecule strategy successfully enhanced the performance of MXene films. • Synergistic effect of ppy and TEMPO is the key to improve performance. • DFT confirms the superiority of pMT composite.